Hornsea Project Three Offshore Wind Farm · 2019. 3. 27. · Checked by Karma Leyland Approved by...

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Hornsea Project Three Offshore Wind Farm Hornsea Project Three Offshore Wind Farm Appendix 26 to Deadline 9 submission - Safety Justification for Single Line of Orientation Layout Date: 26 th March 2019

Transcript of Hornsea Project Three Offshore Wind Farm · 2019. 3. 27. · Checked by Karma Leyland Approved by...

  • Hornsea Project Three Offshore Wind Farm

    Hornsea Project Three

    Offshore Wind Farm

    Appendix 26 to Deadline 9 submission - Safety Justification for Single Line of Orientation Layout

    Date: 26th March 2019

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    Document Control

    Document Properties

    Organisation Ørsted Hornsea Project Three

    Author Anatec

    Checked by Karma Leyland

    Approved by Andrew Guyton

    Title Safety Justification for Single Line of Orientation Layout

    PINS Document Number

    n/a

    Version History

    Date Version Status Description / Changes

    18.03.2019 A Draft Compilation of NRA and Examination Submissions Supporting a Single Line of Orientation.

    26/03/2019 B FINAL Compilation of NRA and Examination Submissions Supporting a Single Line of Orientation submitted at Deadline 9

    Ørsted

    5 Howick Place,

    London, SW1P 1WG

    © Orsted Power (UK) Ltd, 2019. All rights reserved

    Front cover picture: Kite surfer near a UK offshore wind farm © Ørsted Hornsea Project Three (UK) Ltd., 2019.

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    Table of Contents

    1. Introduction ................................................................................................................................................. 1

    Background ..................................................................................................................................................... 1

    Purpose of this Report .................................................................................................................................... 1

    2. Project Details ............................................................................................................................................ 1

    3. Guidance .................................................................................................................................................... 3

    4. Consultation ............................................................................................................................................... 3

    Maritime and Coastguard Agency ................................................................................................................... 3

    Trinity House ................................................................................................................................................... 4

    Cruising Association ....................................................................................................................................... 4

    Royal Yachting Association ............................................................................................................................ 4

    Regular Operators .......................................................................................................................................... 5

    5. Vessel Traffic .............................................................................................................................................. 6

    Data Overview ................................................................................................................................................ 6

    Traffic Density at Hornsea Developments ....................................................................................................... 9

    Anchoring Activity within Array Area ............................................................................................................. 10

    Traffic Behaviour Internally within Existing Arrays ........................................................................................ 10

    6. Search and Rescue .................................................................................................................................. 12

    Mark Prior Bio ............................................................................................................................................... 13

    Search and Rescue Access Lanes ............................................................................................................... 13

    Lack of Precedent ......................................................................................................................................... 13

    Turning Within the Array ............................................................................................................................... 13

    Minimum Spacing ......................................................................................................................................... 15

    7. Historical Incidents ................................................................................................................................... 15

    8. Other Evidence ......................................................................................................................................... 20

    Mitigation Measures – Pre Submission ......................................................................................................... 20

    Mitigation Measures – Post Submission ....................................................................................................... 21

    SOLAS Obligations ....................................................................................................................................... 22

    Hornsea Three as a Standalone Development ............................................................................................. 22

    Internal Allision Risk Impact from Navigational Risk Assessment ................................................................. 23

    9. Other Constraints ..................................................................................................................................... 31

    10. Summary and Conclusion ........................................................................................................................ 32

    11. References ............................................................................................................................................... 34

    List of Tables

    Table 2.1 Key project parameters ................................................................................................................ 2 Table 5.1: Traffic density within each Hornsea development array area ....................................................... 9

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    Table 6.1: EASA Part SERA recommended speeds ................................................................................... 14 Table 6.2 Minimum spacing at UK offshore wind farm developments ........................................................ 15 Table 6.3: Summary of historical collision and allision incidents involving wind farm sites ......................... 18 Table 7.1: Effects associated with navigation internally within the Hornsea Three array area .................... 29

    List of Figures

    Figure 2.1 Overview of NRA layout ............................................................................................................... 2 Figure 5.1 Overview of vessel traffic data within 10 nm of Hornsea Three array area (40 days summer and

    winter 2016) ................................................................................................................................. 7 Figure 5.2 Recreational vessels within 10 nm of Hornsea Three array area (40 days summer and winter) .. 8

    Figure 5.3 Fishing vessels within 10 nm of Hornsea Three array area (40 days summer and winter) .......... 9 Figure 5.4: AIS recreational vessels within London Array site boundary (Mar 2016 to Feb 2017) ............... 11 Figure 5.5: AIS fishing vessels within London Array site boundary (Mar 2016 to Feb 2017) ........................ 12 Figure 6.1 Historical SAR incidents within 10 nm of Hornsea Three array area .......................................... 16 Figure 6.2 MAIB incident locations by incident type within 10 nm of Hornsea Three array area ................. 17 Figure 6.3 RNLI incident locations by incident type within 10 nm of Hornsea Three array area .................. 18 Figure 7.1: GMDSS sea areas ..................................................................................................................... 24

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    1. Introduction

    Background

    Guidance provided in the Maritime and Coastguard Agency’s (MCA) Marine Guidance Note

    (MGN) 543 states ‘Developers should plan for at least two lines of orientation unless they can

    clearly demonstrate that fewer is acceptable’. Using this guidance as a basis, the Applicant has

    been assessing layouts and layout strategies for over two years as part of the Environmental

    Impact Assessment (EIA) process. Following the Preliminary Environmental Impact Assessment

    (PEIR) and responses received as part of the Section 42 consultation, the Applicant moved, in

    consultation with the MCA and Trinity House (TH), to firstly develop a set of Layout Development

    Principles to provide a framework for post consent layout approval and secondly to base the

    Navigational Risk Assessment (NRA) and the Environmental Statement on a layout with a single

    line of orientation (SLoO).

    As reflected at Deadline 4 responses, as part of the Hornsea Three Examination phase both the

    MCA and TH agreed that a single line of orientation would be acceptable if a suitable safety

    justification was presented and agreed. The Applicant clarified that its safety justification was

    presented in the Navigational Risk Assessment (NRA) dated May 2018, as supplemented with

    information requested by the MCA and TH during the examination. At the Issue Specific Hearing

    (ISH) on the 7th March 2019 submissions made by TH indicated that it would be helpful to have the

    safety justification in one document. In response the Applicant agreed to represent the work

    undertaken as part of the NRA and also the technical submissions into the examination process

    from the Search and Rescue (SAR) Helicopter Specialist into one document comprising the safety

    justification for a SLoO. This document serves that purpose and demonstrates how fewer than two

    lines of orientation is ’acceptable’ (as defined in accordance with MGN 543) for Hornsea Three.

    Purpose of this Report

    This report serves as the safety justification which the MCA have requested in line with Principle 3

    of the Layout Development Principles. The report shows that a SLoO incorporated into the

    Hornsea Three array layout is ’acceptable and safe’ (as defined in accordance with MGN 543) by

    summarising relevant information given in Volume 5, Annex 7.1: Navigational Risk Assessment of

    the Environmental Statement (hereafter referred to as the “NRA”) and materials produced since

    the NRA was submitted as part of the examination process.

    2. Project Details

    The layout considered in the NRA is shown in Figure 2.1. The symbology used in Figure 2.1 for

    turbine locations has been designed to give a clearer idea of the size of the turbines in relation to

    the Hornsea Three array area as a whole.

    The layout consisted of the following 319 structures:

    • 300 turbines;

    • 12 offshore High Voltage Alternating Current (HVAC) transformer substations;

    • Four offshore High Voltage Direct Current (HVDC) converter substations; and

    • Three accommodation platforms.

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    The minimum structure spacing in the NRA layout is 1,000 m. Key project parameters provided in

    the NRA are summarised in Table 2.1.

    Figure 2.1 Overview of NRA layout

    Table 2.1 Key project parameters

    Parameter Updated Application Value

    Maximum number of turbines 300

    Maximum number of other structures 19 (see above for breakdown)

    Maximum blade tip height (above Lowest Astronomical Tide (LAT))

    250 m

    Maximum hub height (above LAT) 153 m

    Maximum rotor diameter 195 m

    Minimum spacing 1,000 m

    Minimum blade clearance (above LAT) 34.97 m

    Worst case foundation for shipping and navigation Jacket

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    3. Guidance

    Section 2 of the NRA outlines the guidance and legislation used to inform the assessment. This

    includes MGN 543 which, as noted in Section 1, advises that a SLoO layout will be agreed if

    demonstrated to be acceptable. However, there are no parameters within the guidance to identify

    what is acceptable and so this has been assumed based on both early consultation and the MCA’s

    remit that the developer must demonstrate that the risk is As Low As Reasonably Practicable

    (ALARP) in line with the MCAs own methodologies1 which the MCA require to be a template when

    preparing NRAs. For clarity this methodology has been used for the NRA for Hornsea Three.

    Although not referenced by either guidance document, the MCA have recently noted during

    examination that geotechnical constraints may be used to aid the justification for a SLoO, i.e.

    demonstrating that it is not physically possible to apply two lines of orientation2.

    As demonstrated in section 4, this safety justification has been built upon the safety of both surface

    craft and SAR aircraft and is therefore in accordance with MGN 543.

    4. Consultation

    Throughout the consenting process for Hornsea Three consultation has been undertaken with

    relevant shipping and navigation stakeholders including the MCA. This section provides detail of

    consultation undertaken relevant to the topic of the array layout, including consultation summarised

    in the NRA.

    Maritime and Coastguard Agency

    During a consultation meeting in February 2017, both the MCA and Trinity House (TH) were clear

    that MGN 543 states that developers should plan for two lines of orientation in the Hornsea Three

    array layout unless they can clearly demonstrate that fewer is acceptable and safe for SAR

    helicopter operations. In consultation with the MCA, the Applicant subsequently took the decision

    to progress the final NRA based upon a SLoO layout.

    During a consultation meeting in December 2017, the key points of the safety justification for a

    SLoO were discussed. These key points are listed below alongside where they are addressed in

    greater detail within this report.

    • Agreement between Hornsea Three and the MCA that vessel traffic levels were low within the

    array area (section 5 – traffic density at Hornsea developments);

    • Fishing stakeholders are more concerned with minimum spacing and foundation types than

    array layout (section 4 – regular operators);

    1 Methodology for Assessing the Marine Navigational Safety Risk & Emergency Response Risks of Offshore Renewable Energy Installations (OREI) (MCA, 2016). 2 MCA’s Responses to the Examining Authority’s request for further information (Rule 17) (REP7-102)

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    • Hornsea Three resources will be on site and most likely to respond to an incident (section 8 –

    International Convention for the Safety of Life at Sea (SOLAS) obligations); and

    • No other project borders the Hornsea Three array area (section 8 – Hornsea Three as a

    standalone development).

    Trinity House

    During a consultation meeting in December 2017, TH viewed the change to a SLoO as “a positive

    step forward” compared to the irregular layout assessed in the Preliminary Environmental

    Information Report (PEIR) and did not express a need for further refinement to two lines of

    orientation. At this meeting TH agreed that commercial vessels will not navigate within the array.

    The Applicant noted their commitment to a SLoO and added that a safety justification supporting a

    SLoO would be included within the NRA.

    Cruising Association

    During consultation the Cruising Association (CA) has stated that they have no major issues with

    the development of Hornsea Three and noted that many yachtsman will choose not to transit

    through an offshore wind farm. Furthermore, the CA felt that the additional time and distance

    incurred as a result of avoiding the array would mostly be minimal and it is likely that yachts and

    recreational craft may at the time of passage choose to avoid or be in a position where they should

    avoid the array.

    The CA commented that Hornsea Three is located in an area of very light yachting and

    recreational traffic. This is in agreement with the vessel traffic data assessed in the NRA which

    provides very low numbers of recreational vessel movements. Although “straight see-through

    channels between the turbines” are preferable, the CA confirmed that any disadvantage for not

    doing so “may prove minimal and therefore acceptable to many”.

    In their Section 42 response the CA noted that the layout of structures should be in straight lines

    following a rectangular or similar pattern, although their view was eased by the adoption of a

    minimum spacing of 1,000 metres (m) or greater. Any consequent disorientation of helmsman can

    be mitigated to an extent by additional marking and lighting. As per the NRA, structures in the

    array will be marked and lit in accordance with IALA Recommendation O-139 on The Marking of

    Man-Made Offshore Structures (IALA, 2013) and TH and the MCA will be consulted in relation to

    the need for additional internal aids to navigation.

    In the SoCG between Hornsea Three and the CA the CA agree that Hornsea Three has minimal

    impacts on recreational craft and are therefore in agreement with the Layout Development

    Principles approach being developed in conjunction with the MCA and TH.

    Royal Yachting Association

    During consultation the Royal Yachting Association (RYA) expressed no concerns given that the

    level of recreational activity at the distance offshore of the Hornsea Three array area is very low.

    The RYA added that at the distance offshore any recreational user would be very experienced and

    well-equipped. It is noted that the RYA had no concerns with the indicative layouts which were

    presented at the PEIR stage. The PEIR layouts included no lines of orientation (irregular).

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    The RYA were provided but had no comments with regard to the Environmental Statement and

    NRA.

    Regular Operators

    Regular operators were identified in the NRA using the Automatic Identification System (AIS) traffic

    data and were invited to comment on the development and attend a Hazard Workshop held at the

    Ørsted offices in London in February 2017.

    Regular operators whose representatives attended the Hazard Workshop included the following:

    • DFDS Seaways;

    • Aggregate Industries UK;

    • DEME Building Materials;

    • Centrica (now Spirit Energy);

    • Vroon Offshore Services; and

    • Dutch Fishing Association VISNED.

    It is also noted that a representative from the MCA was present at the Hazard Workshop.

    During the meeting, all commercial operators present agreed that commercial vessels (non-fishing)

    would not use the array area for transiting. Specifically, both DFDS Seaways and marine

    aggregate dredger representatives confirmed that the array layout is a non-issue since their

    vessels would not enter the array area. Oil & Gas representatives stated that their support vessels

    would choose to use the navigational corridor between the Hornsea developments rather than

    transit through the array area, noting that this would not significantly increase routeing distances.

    Although not in attendance at the Hazard Workshop, commercial ferry operator KESS expressed

    similar views, noting a slight impact on routeing but that vessels can avoid the area and therefore

    there are no notable safety concerns.

    VISNED noted that fishing activity would be possible within the indicative layout presented at the

    PEIR stage (an irregular layout with no lines of orientation) and commented that “for fishing, the

    separation between turbines is more important than the regularity of the layout”. Demersal trawlers

    active within the array are expected to target specific fishing grounds meaning that it is unlikely that

    the skippers would choose to fish along a fixed line of orientation in the array layout.

    VISNED also noted that in good weather fishing vessel are likely to transit through the array. It is

    noted that Dutch fishing vessels (represented by VISNED) are predominant in the area.

    Regular operator consultation clearly indicates that, with the exception of fishing vessels,

    commercial traffic would be unlikely to transit through the array and therefore there is no, or

    minimal, additional benefit to safe surface navigation by including two lines of orientation in the

    array layout. In the case of fishing vessels the NRA remarks that the majority of risk associated

    with internal navigation is related to vessels engaged in fishing rather than transiting.

    In summary, it is clear that no consultee expressed concerns from a safety perspective or

    otherwise in relation to a SLoO.

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    5. Vessel Traffic

    Data Overview

    The NRA included a baseline navigation review of the Hornsea Three array area using marine

    traffic data. The dataset analysed consisted of a combined dataset of 40 days of AIS, visual and

    Radar data recorded within 10 nautical miles (nm) of the array area (the “study area”) from survey

    vessels working at the Hornsea Three array area during summer (26 days) and winter (14 days)

    2016. This data satisfied MCA requirements as set out in MGN 543 and was approved by the MCA

    in April 2017.

    All Vessels

    Plots of the vessel tracks recorded during each survey period, colour-coded by vessel type, and

    excluding temporary traffic (such as the survey vessels and traffic associated with temporary

    drilling rigs) is presented in Figure 5.1 (Panels A and B). Figure 5.1 also presents the

    corresponding density grid for each survey period (Panels C and D).

    For the 26 days analysed in summer 2016, there was an average of 42 unique vessels per day

    passing within the study area. In terms of vessels intersecting the Hornsea Three array area, there

    was an average of 15 unique vessels per day. The majority of tracks were cargo vessels (33% of

    traffic within the Hornsea Three array area) and fishing vessels (30%).

    For the 14 days analysed in winter 2016, there was an average of 28 unique vessels per day

    passing within the Hornsea Three array area study area. In terms of vessels intersecting the

    Hornsea Three array area, there was an average of 13 unique vessels per day. The majority of

    tracks were cargo vessels (45% of traffic within the Hornsea Three array area) and tankers (21%).

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    Figure 5.1 Overview of vessel traffic data within 10 nm of Hornsea Three array area (40 days summer and winter 2016)

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    Recreational Vessels

    A plot of the recreational vessel tracks recorded throughout the survey period is presented in

    Figure 5.2. It is noted that 45% of all recreational activity was recorded over a period of two days

    when an annual sailing race passed through the Hornsea Three array area.

    Figure 5.2 Recreational vessels within 10 nm of Hornsea Three array area (40 days summer and winter)

    Fishing Vessels

    A plot of the fishing vessel tracks recorded throughout the survey period is presented in Figure 5.3.

    It can be seen that fishing vessels were tracked transiting through the Hornsea Three array area

    as well as actively engaged in fishing activity.

    Fishing vessel sightings (over flight and/or vessel-based) and satellite data (from the MMO) was

    used to validate the AIS, visual and Radar dataset and showed good correlation.

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    Figure 5.3 Fishing vessels within 10 nm of Hornsea Three array area (40 days summer and winter)

    Traffic Density at Hornsea Developments

    Table 5.1 summarises the density of vessel traffic recorded on AIS, visual and Radar during the

    NRA surveys undertaken for each Hornsea development, noting that the data for each NRA was

    approved by the MCA.

    Table 5.1: Traffic density within each Hornsea development array area

    Development

    Surface Area

    of Array Area

    (nm2)

    Average Unique Vessels per Day Within Array Area

    Traffic Density (Daily Vessels

    per nm2) Summer Winter All

    Hornsea Project One

    118 12 13 12 0.10

    Hornsea Project Two

    134 12 12 12 0.09

    Hornsea Three 202 15 13 14 0.07

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    It can be seen that the levels of vessel traffic for each Hornsea development was similar with

    Hornsea Three giving the highest average number of unique vessels per day by a small margin.

    However, when accounting for the significantly greater surface area covered by the Hornsea Three

    array area (71% greater than Hornsea Project One and 51% greater than Hornsea Project Two),

    the vessel density is lower at Hornsea Three than at the other Hornsea developments.

    Moreover, it is noted that the AIS data used for Hornsea Three was collected in 2016 at which

    point all fishing vessels of length greater than 15 m were required to carry AIS equipment as per

    Annex II of European Union (EU) Directive 2002/59/EC. This compares with length thresholds of

    45 m and 24 m at the time of data collection for Hornsea Project One (2011) and Hornsea Project

    Two (2012), respectively. Therefore, given the significant presence of fishing vessels in all three

    Hornsea developments, in reality the traffic density for Hornsea Project One and Hornsea Project

    Two may be significantly higher than that of Hornsea Three.

    With increasing experience and knowledge of navigation by SAR assets within offshore wind

    farms, the Applicant understands that precedence should not be set with respect to the number of

    lines of orientation in a layout. However, both Hornsea Project One and Hornsea Project Two had

    layouts approved by the MMO in consultation with the MCA with a SLoO (noting vessel density

    being greater than that of Hornsea Three). Therefore, from the perspective of local vessel traffic

    and impacts on surface navigation, it is considered reasonable for Hornsea Three to also be

    consented with a SLoO.

    Anchoring Activity within Array Area

    As part of the vessel analysis undertaken in the NRA, an assessment was undertaken to identify

    anchoring activity within a 10 nm buffer of the Hornsea Three array area. Considering both vessels

    broadcasting an “at anchor” status and vessels travelling at speeds of less than one knot (kt) for

    more than 30 minutes no vessels were deemed to be at anchor. This may be attributed to the

    distance offshore and the moderate water depth.

    This finding adds further weight to the information provided in the previous section that vessel

    activity within the Hornsea Three array area is relatively low.

    Traffic Behaviour Internally within Existing Arrays

    London Array Offshore Wind Farm has been fully operational since 2013 and was consented

    within a busy and seasonal area for small craft. A specific buoyed navigation channel (Fouglars

    Gat) was designed in the position of an existing preferred route, although does not form part of

    either of the primary lines of orientation in the array layout. The minimum turbine spacing at

    London Array is approximately 650 m.

    As part of the Hornsea Three NRA, a year of AIS data, collected between March 2016 and

    February 2017, was analysed within the London Array site boundary in order to gain an

    understanding of the behaviour of vessel traffic transiting internally within an array.

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    Figure 5.4 presents the recreational vessel tracks recorded within the London Array site boundary.

    During the one-year period 140 unique recreational transits were recorded, all but eight tracks

    transited through Foulgers Gat for the majority of their transit; these vessels generally made

    passage in straight lines using the buoyed navigation channel. Of those eight tracks which did not

    fully stay within Foulgers Gat, passage was not necessarily in straight lines, and was not dictated

    by the available lines of orientation.

    Figure 5.4: AIS recreational vessels within London Array site boundary (Mar 2016 to Feb 2017)

    Figure 5.5 presents the fishing vessel tracks recorded within the London Array site boundary. Only

    32 unique fishing vessel transits were recorded. Of the 49 tracks recorded, 23 broadcast a

    navigational status of “engaged in fishing”, with these near the southern boundary; the remaining

    26 tracks consisted of passages through the array, with vessels not, in the majority, following the

    main lines of orientation. This is reflective of comments from fishing representatives during

    consultation, as noted in section 4.

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    This technical evidence provides useful context re the MCA’s assertion that the safest way to

    navigate through an offshore wind farm is when multiple lines of orientation are in place (see MCA

    consultation in section 2), with vessels at London Array opting to take alternative routes which are

    not necessarily confined to the available lines of orientation. Moreover, evidence suggests that

    larger commercial vessels are not likely to navigate through an offshore wind farm; this is

    evidenced by extensive traffic surveys and has been reiterated by commercial operators over

    many years during consultation for many developments. As noted in section 4 (Regular

    Operators), this is also the case for Hornsea Three, with large commercial operators in the area

    such as DFDS Seaways making clear during consultation that they would not make passage

    through the array.

    Figure 5.5: AIS fishing vessels within London Array site boundary (Mar 2016 to Feb 2017)

    6. Search and Rescue

    Extensive technical assessment has been undertaken on the impact of Hornsea Three on the

    ability of SAR helicopters to undertake operations within the array area, led by Mark Prior, SAR

    Helicopter Specialist. Appendix 14 to the Applicant’s Deadline 2 submission provides an in-depth

    analysis of the impact the development may have on SAR accessibility; some of the key points

    raised are outlined in the following subsections.

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    Mark Prior Bio

    Mark Prior is a highly experienced aviation professional with a wide range of expertise in

    certification, safety analysis, investigation, operations, technical issues and regulations. Over 38

    years’ experience as a pilot, initially in the Royal Air Force (RAF), then as a licensed civil pilot with

    concurrently 25 years of experience as an Experimental Test Pilot. Since 2003 mark has been an

    industry representative on a number of rule-making, operational and research groups.

    Search and Rescue Access Lanes

    From Annex 5 to MGN 543, a SAR access lane is an area within which “there shall be no OREIs,

    or other structures, in the wind farm or on the boundary that present an obstacle or risk to SAR

    helicopters flying along”. The purpose of a SAR access lane is to ensure that “a SAR helicopter

    can fly from one side of a wind farm to the other”. Furthermore, “the lanes also provide safer and

    more predictable paths through a wind farm for surface rescue vessels”.

    Lack of Precedent

    No current experience exists with SAR aviation operations in UK offshore wind farm, with only

    trials undertaken to date which have not incorporated Round 3 offshore wind farms, with the

    exception of at Rampion Offshore Wind Farm (3.6 MW turbines in a grid layout). In particular, there

    is no experience of conducting a search in an array where the turbines are spaced at least

    one kilometre (km) apart and current Standard Operating Procedures (SOP) are based on more

    tightly packed arrays, which will be of limited validity for Hornsea Three. However, the MCA have

    conducted flights with spacing around 800 to 900 m to explore SAR issues.

    In some ways a parallel can be drawn to searching in hilly terrain where the helicopter can be

    constrained to valleys when the hill tops are covered in cloud. Unlike hilly terrain, all obstacles in a

    turbine array will be controlled, accurately mapped and information provided to the crew by paper

    and electronic means. The MCA, and their helicopter contractor, are able to modify their search

    profiles and procedures to take account of the obstacle environment presented in Round 3

    offshore wind farm arrays.

    Turning Within the Array

    The MCA provided data to the Applicant from a trial conducted by their SAR helicopter contractor

    over Loch Ness in Scotland during the summer of 2018. Conducting such trials is problematic and

    can require the use of specialist tracking equipment in order to produce accurate and repeatable

    results. The Applicant raised a concern that the single image provided by the MCA appeared to

    show turns at an inconsistent angle of bank as the orbits were not round, despite it being stated

    that the turns were flown in zero wind. Furthermore, it did not appear to show the diameter being

    measured accurately.

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    The MCA later provided two diagrams showing turning performance. The first showed a turn into a

    40 kt wind with the wind 30 degrees (°) to the right of track. The radius of turn for a 180° turn of

    0.12 nm coincides with the Applicant’s calculations. A second diagram with the 40 kt wind at 90° to

    the right showed a reduced turning radius for a 180° turn of 0.1 nm. These diagrams support the

    Applicant’s calculations of turning circle. The Applicant used weather data from the J6A platform

    and seven years’ worth of met data from the Hornsea Project One array area to confirm that

    simultaneous occurrences of poor visibility and strong winds were extremely uncommon. The J6A

    met data for one year had no occurrences of visibility below 1000 m and wind speed above 30 kt,

    whilst the Hornsea Project One data, recorded at 10 minute intervals for seven years, had a

    probability of 0.0166% of strong winds and poor visibility occurring concurrently.

    The European Aviation Safety Agency (EASA) Part Standardised European Rules of the Air

    (SERA) is used for guidance as to the speeds flown against visibility. Although an advisory

    airspeed is provided, this is really the ground speed, as that determines the closure rate with

    obstacles. Table 6.1 gives the recommended speeds for differing levels of visibility.

    Table 6.1: EASA Part SERA recommended speeds

    Visibility (m) Advisory speed (kt) Time to cover “visible distance” at “advisory speed” (seconds)

    800 50 31

    1,500 100 29

    2,000 120 32

    With visibility in excess of 1,000 m, the turbine ahead, and laterally, will be visible and so a turn

    can be made without risk of colliding with the turbine. With visibility below 1,000 m, the airspeed

    will be reduced towards 50 kt, requiring a smaller distance to turn.

    The MCA have suggested that a turn would likely be undertaken with an angle of bank of 20 to

    30°, with the greatest speed applied 80 kt (where visibility is good). The MCA have also suggested

    that 1 nm is required to allow sufficient space to turn an aircraft, particularly in poor weather.

    Classic aerodynamic theory shows that:

    𝑟 =𝑣2

    𝑔 tan ∅

    Where:

    𝑟 = 𝑟𝑎𝑑𝑖𝑢𝑠 𝑜𝑓 𝑡𝑢𝑟𝑛 (𝑚)

    𝑔 = 9.81𝑚/𝑠2

    𝑣 = 𝑡𝑟𝑢𝑒 𝑎𝑖𝑟𝑠𝑝𝑒𝑒𝑑 (𝑘𝑡)

    ∅ = 𝑎𝑛𝑔𝑙𝑒 𝑜𝑓 𝑏𝑎𝑛𝑘 (°)

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    Applying this to a turn at 80 kt with angle of bank 20°, the radius of turn would be approximately

    0.25 nm (diameter 0.50 nm). In poor visibility the airspeed would be reduced, and thus the radius

    of turn would also be reduced. The MCA and Applicant have different positions on whether a

    Helicopter Refuge Area is essential. However, agreement reached on Principle 5 does provide for

    a Helicopter Refuge Area whose exact dimensions will be determined post consent.

    Minimum Spacing

    Table 6.2 presents the minimum spacing at a number of operational or under construction offshore

    wind farms in the UK. Values are based on distances obtained from United Kingdom Hydrographic

    Office (UKHO) Admiralty charts.

    Table 6.2 Minimum spacing at UK offshore wind farm developments

    Development Minimum Turbine Spacing

    within NRA (m) Increase in Minimum Turbine

    Spacing at Hornsea Three

    Hornsea Project One 878 13.9%

    Hornsea Project Two 924 8.23%

    East Anglia One 675 48.2%

    East Anglia Three 675 48.2%

    Rampion 600 66.7%

    London Array (Round 2 development) 650 53.9%

    The minimum spacing between turbines for Hornsea Three of 1,000 m is greater and in some

    cases significantly greater than other offshore wind farms in the UK. The two other Hornsea

    developments are the only cases where the minimum spacing is somewhat similar and layouts for

    these developments have a SLoO.

    The greater minimum spacing gives vessels more sea room to navigate and manoeuvre within the

    Hornsea Three array area (including turning circles and rates of turn).

    Given the distance offshore and the presence of project vessels for Hornsea Three the likelihood

    of a SAR operation in which a widespread search is required is very low. Helicopter Refuge Areas

    are intended to support access to, and within, the array area, including in the instance that a

    medical evacuation is required.

    7. Historical Incidents

    The NRA considers SAR operations data within the Hornsea Three array area study area and

    found that in the five-year period between 2011 and 2015 a total of nine SAR operations were

    recorded, as shown in Figure 7.1.

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    Figure 7.1 Historical SAR incidents within 10 nm of Hornsea Three array area

    Only one of these SAR operations was recorded within the Hornsea Three array area and all the

    incidents involved a medical rescue conducted in the daytime without the need for a search. From

    this data it is evident that the region within the southern North Sea where Hornsea Three is to be

    located does not endure a high level of marine incidents which require SAR operations. This will be

    furthered by the presence of Hornsea Three since project vessels will be fully certified and very

    likely able to render assistance under SOLAS obligations in addition to a SAR Asset (see section 8

    – SOLAS Obligations), and in the case of less protracted incidents may be able to provide a

    sufficient response without the need for a SAR Asset. Further discussions will take place with the

    MCA post consent as part of the ERCoP on emergency response requirements.

    In addition to incidents involving SAR operations, the NRA also analysed incident data provided by

    the Maritime Accident Investigation Branch (MAIB) and Royal National Lifeboat Institution (RNLI)

    during the 10-year period between 2005 and 2014.

    Figure 7.2 presents the locations of accidents, injuries and hazardous incidents reported to the

    MAIB within the various study areas considered in the NRA relating to shipping and navigation.

  • Safety Justification for Single Line of Orientation Layout March 2019

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    Figure 7.2 MAIB incident locations by incident type within 10 nm of Hornsea Three array area

    A total of five unique incidents, with one incident involving two vessels, were reported within the

    Hornsea Three array area study area, corresponding to an average of one incident every two

    years. None of these incidents occurred within the Hornsea Three array area. “Accident to Person”

    was the most frequent incident type and Oil & Gas affiliated vessels were the most frequent

    casualty type.3

    Figure 7.3 presents the locations of incidents responded to by the RNLI within the various study

    areas considered in the NRA relating to shipping and navigation.

    It was found that no launches to incidents were reported by the RNLI within the Hornsea Three

    array area study area with the closest incident approximately 215 m outside of the study area. This

    reflects the strategic performance standard of the RNLI of reaching casualties up to a maximum of

    100 nm from shore – the RNLI may respond to a drifting vessel but are unlikely to respond to a life-

    saving incident in proximity to the Hornsea Three array area owing to the time it would take to get

    to the incident from shore.

    3 It is noted that construction and operations of Hornsea Three may lead to potential industry incidents requiring SAR response; however this is related to the wind farm rather than the internal layout. All wind farm personnel will be issued with Personal Locator Beacons (PLBs) and will be required to wear these when engaged in activities that present an elevated risk, which should assist the SAR helicopter with pinpointing the casualty.

  • Safety Justification for Single Line of Orientation Layout March 2019

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    Figure 7.3 RNLI incident locations by incident type within 10 nm of Hornsea Three array area

    The NRA also considers historical collision and allision incidents involving offshore wind farms.

    Research found that there were 13 incidents between 2005 and 2016, as detailed in Table 7.1.

    The majority of incidents resulted in minor or moderate damage to the casualty vessel and no

    serious injuries were reported. The MCA has indicated that there have been additional incidents

    since 2016.

    It is noted that the cause of each of the incidents detailed in Table 7.1 was not related to the layout

    of the wind farm structures. Causes typically involved negligence by persons, such as misuse of

    the auto-pilot. Therefore for these incidents the presence of multiple of lines of orientation would

    not have prevented the incident and thus it is anticipated that a SLoO would be sufficient for

    minimising the risk of a collision or allision incident.

    Table 7.1: Summary of historical collision and allision incidents involving wind farm sites

    Project or third party

    Incident type Date

    Damage to vessel (as per the incident

    reports)

    Injury to person

    Source

    Project Allision – service vessel with turbine

    7 August 2005 Minor damage to gangway on the vessel

    No injury

    Maritime Accident Investigation Branch (MAIB)

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    Project or third party

    Incident type Date

    Damage to vessel (as per the incident

    reports)

    Injury to person

    Source

    Project Allision – service vessel with turbine

    29 September 2006

    No damage to vessel

    No injury MAIB

    Project

    Allision – service vessel with disused pile

    8 February 2010

    Minor damage to vessel

    Injury MAIB

    Third party and project in harbour

    Collision – service vessel with vessel

    23 April 2011 Moderate damage to vessel

    No injury MAIB

    Project Allision – service vessel with turbine

    18 November 2011

    Major damage to vessel

    No injury MAIB

    Project

    Collision – service vessel with service vessel

    2 June 2012 Moderate damage to vessel

    No injury

    UK Confidential Reporting Programme for Aviation and Maritime (CHIRP)

    Project

    Allison – service vessel collision with OWF structure

    20 October 2012

    Minor damage to vessel

    No injury MAIB

    Project Allision – service vessel with buoy4

    21 November 2012

    Major damage to vessel

    No injury MAIB

    Project Allision – service vessel with turbine

    21 November 2012

    Moderate damage to vessel

    Injury MAIB

    Project Allision – service vessel with turbine

    16 February 2013

    Minor damage to vessel

    No injury UK CHIRP

    4 Previously this incident was listed as being with a turbine but the MCA have provided clarification.

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    Project or third party

    Incident type Date

    Damage to vessel (as per the incident

    reports)

    Injury to person

    Source

    Project

    Allision – service vessel with turbine

    July 2013 Minor damage to vessel

    No injury

    International Marine Contractors Association (IMCA) Safety Flash

    Project Allision – service vessel with turbine

    14 August 2014 Minor damage to vessel and pollution

    No injury UK CHIRP

    Third party Allision – fishing vessel with turbine

    26 May 2016 Moderate damage to vessel

    Injury Web search (BBC, 2016)

    8. Other Evidence

    Mitigation Measures – Pre Submission

    The NRA includes an extensive list of mitigation measures adopted as part of Hornsea Three,

    including both embedded mitigation measures and additional mitigation measures required to bring

    specific risks to ALARP. The following list outlines mitigation measures which are relevant to the

    case that a SLoO is sufficient for Hornsea Three, noting the NRA assessed a SLoO:

    • Charting of Hornsea Three array area – the Hornsea Three array area will be marked on

    relevant UKHO Admiralty charts.

    • Compliance with UK and Flag State regulations and IMO conventions including COLREGs

    and SOLAS – compliance to ensure that standard levels of navigation and vessel safety

    continue to be adhered to by all project related vessels during all phases. SOLAS is

    discussed in further detail in the next section.

    • ERCoP – an ERCoP will be developed and implemented for all phases of the project. The

    array layout and SAR Access Lanes (compliant with the Layout Development Principles) will

    be included as standard.

    • IALA guidance and Aids to Navigation – structures within the wind farm will be marked and lit

    in accordance with IALA Recommendation O-139 on the Marking of Man-Made Offshore

    Structures (IALA, 2013). Other visual and auditory Aids to Navigation may also be

    implemented, and will be placed and characterised in agreement with TH (and MCA) prior to

    the start of construction.

    • Marine coordination – appropriate marine coordination will be in place to ensure that project

    vessels do not present an unacceptable risk to each other or to transiting vessels.

    • Other means of communication to assist third parties – use of offshore Very High Frequency

    (VHF) aerials, AIS transceivers and the on-site vessels.

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    • Shut down procedures – the individual turbines structures will have functions and procedures

    in place for generator shut down in emergency situations.

    • Promulgation of information – information and warnings will be distributed via Notices to

    Mariners and other appropriate media (e.g. Admiralty charts and fishermen’s awareness

    charts) to enable vessels to effectively and safely navigate around the Hornsea Three array

    area. This may include additional consultation above and beyond the minimum standard

    required.

    • Self-help capability – provision of self-help capabilities to deal with wind farm associated

    emergencies. Consideration shall be given to towage, pollution response and man overboard.

    Mitigation Measures – Post Submission

    Agreement (as confirmed at the ISH1 on 14th December 2018) has been reached with TH that AIS

    transmitters may be fitted to turbines in order to assist with SAR operations. The use of AIS will

    provide additional situational awareness to the SAR crew, above and beyond that provided by the

    multiple onboard navigation systems and sensors.

    The version of the Layout Development Principles published in Volume 4, Annex 3.7: Layout

    Development Principles of the Environmental Statement has since been updated following

    discussions with the MCA and TH. The Applicant has made concessions from the version included

    in the Environmental Statement including:

    • Commitment to a Helicopter Refuge Area (HRA) with a width of between 0.5399nm and 1nm

    (rather than 1km);

    • Tolerance of 100 m either side of the centre line of internal development lanes (rather than

    150 m); and

    • Tolerance of 50 m either side of the centre line of perimeter development lanes (rather than

    150 m).

    It is noted that the final SAR Access Lanes will be agreed as part of the Emergency Response

    Cooperation Plan (ERCoP). However, as per the Layout Development Principles, Hornsea Three

    have committed to SAR Access Lanes which shall:

    • Be parallel to turbine development corridors; and

    • Satisfy the minimum width of 500 m required by MGN 543 to facilitate SAR Asset access,

    where this width is measured tip to tip.

    Allow a SAR Asset (at altitudes below 500 feet (ft) to enter the Hornsea Three array area from a

    position outside of the Hornsea Three array area (or outside of a phase) and exit the other side of

    the Hornsea Three array area (or the other side of a phase) without altering its heading or coming

    into close proximity (less than 250 m radius) to any surface infrastructure. With these mitigation

    measures in place the navigational risk posed to a vessel navigating within the array is anticipated

    to be minimal which further negates the need for multiple lines of orientation.

    The Applicant acknowledges that further discussions will be required post consent with the MCA to

    finalise the details of mitigation measures such as the ERCoP.

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    SOLAS Obligations

    Annex 5 of MGN 543 includes the following:

    “International practice for SAR response to persons in distress at sea includes alerting and

    notifying the nearest vessel(s) (this includes small vessels e.g. fishing vessels and leisure craft) to

    an incident location and asking them to render assistance in accordance with the SOLAS

    regulations.”

    In the case of an incident internally within the array a passing vessel may be obliged to navigate

    through the array to render assistance as per SOLAS obligations. In such a case two lines of

    orientation may be helpful for larger vessels navigating the array; however there is anticipated to

    be a large number of accommodation platforms and vessels on site during operation. As per the

    Design Envelope used to inform the NRA, these are as follows:

    • Up to three accommodation platforms or up to four Offshore Support Vessels (OSV) which

    are likely to carry daughter craft;

    • Up to 20 Crew Transfer Vessels (CTV);

    • Supply vessels which are likely to carry daughter craft; and

    • Marine traffic coordination 24/7.

    Given the anticipated vessel support on site throughout the majority of the operation and

    maintenance phase, emergency response impacts can be effectively managed. Accounting for the

    level of resource on site and the relatively low number of third party vessels in the area (see the

    vessel density analysis in section 5), the NRA concluded that it is highly probable that a Hornsea

    Three project vessel would be the first responder to render assistance in the event of an

    emergency internally within the array. Hence it is considered extremely unlikely that a third-party

    vessel would need to enter the Hornsea Three array area under any SOLAS obligation.

    Further consultation will take place with the MCA post consent regarding the emergency response

    capability of project vessels.

    Hornsea Three as a Standalone Development

    Annex 5 of MGN 543 includes the following:

    “Wind farms which are extended, or adjacent developments which are constructed close to each

    other […] All developers involved must undertake to ensure that layouts are harmonised and of the

    same general orientation.”

    Hornsea Three is not an extension of any existing offshore wind farms. Hornsea Project One and

    Hornsea Project Two are located adjacently to Hornsea Three, but these other developments are

    separated from Hornsea Three by a navigational corridor of 3.9 nm width and therefore Hornsea

    Three should be perceived as a stand-alone array. There are no future developments planned

    which would alter this.

    Since Hornsea Three is considered a standalone development, there are no existing lines of

    orientation which the array is obligated to follow.

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    23

    Internal Allision Risk Impact from Navigational Risk Assessment

    As well as providing the evidence supporting a SLoO, the NRA also assessed the allision risk for

    vessels navigating internally within the Hornsea Three array area. The following subsections

    replicate the commentary provided in the NRA and the assessment undertaken in the ES for each

    phase of the project. It should be noted that much of the evidence outlined in the preceding

    sections is used here. The MCA agreed with the impact assessment presented in the NRA. The

    evidence procured since the NRA (in particular the SAR operations work undertaken by Mark

    Prior) shows agreement with the NRA’s findings.

    Construction and Decommissioning Phases

    The presence of infrastructure within the Hornsea Three array area may cause an increase in

    allision risk for vessels navigating internally within the Hornsea Three array area; however during

    the construction and decommissioning phases measures adopted as part of Hornsea Three will

    ensure that the risk is within tolerable limits.

    Mitigation measures adopted as part of Hornsea Three include:

    • Buoyed construction (or decommissioning) area clearly identifying the location of construction

    (or decommissioning) works and vessels;

    • For areas where active platform or turbine construction (or decommissioning) activities are

    occurring, 500 m safety zones will be in place to protect both construction and third party

    vessels. Additionally, 50 m pre-commission safety zones will be used to ensure users are

    aware of the risk associated with approaching pre-commissioned turbines;

    • A Marine Coordination Centre will fully manage vessels movements associated with Hornsea

    Three (although command of each vessel remains with each individual Master); and

    • Extensive promulgation of information.

    Experience of wind farm construction for developers, contractors and vessel operators is now

    extensive, with a number of operational wind farms located within dense shipping areas. Hornsea

    Three shall be monitored throughout construction by the Marine Coordination Centre using VHF

    and AIS but also through the presence of construction (or decommissioning) vessels. Currently

    Hornsea Three is out-with the Global Maritime Distress and Safety System (GMDSS) sea area A1,

    but is within sea area A2 meaning that only Medium Frequency (MF) calling or satellite

    communications are available with shore (see Figure 8.1).

    However MF and satellite communications are not generally carried by recreational vessels or

    other smaller vessels due to the high cost of equipment. Therefore, the presence of the Marine

    Coordination Centre, offshore VHF aerials, AIS receivers and the presence of on-site construction

    vessels (or decommissioning vessels) will provide benefits for communication, monitoring and

    SAR. Should a vessel on site require assistance, then Hornsea Three vessels, including under

    SOLAS obligations, are beneficially placed to provide information and assets including navigational

    information (including weather forecasting) and safety support. This will be discussed further with

    the MCA post consent.

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    When considering the mitigation measures adopted as part of Hornsea Three, and the positive

    effects associated with the presence of the Hornsea Three array area, the risk of allision within the

    Hornsea Three array area during construction is assessed to be broadly acceptable (minor

    adverse significance in the Environmental Statement).

    Figure 8.1: GMDSS sea areas

    Operation and Maintenance Phase

    Project Vessels

    Any vessel and crew present within the Hornsea Three array area during the operation and

    maintenance phase shall have a level of competence pre-determined by the Hornsea Three Safety

    Management Systems (SMS) and their own Flag State regulations. It is noted that, given the size

    of vessels required for the distance offshore of the Hornsea Three array area (65.3 nm), vessels

    will typically be larger than previously seen at offshore wind farm developments closer to the coast,

    and will be fully certified as per flag state requirements. MGN 280 Small Vessels in Commercial

    Use for Sport or Pleasure, Workboats and Pilot Boats – Alternative Construction Standards (MCA,

    2004) requires vessels operating over 60 nm from a safe haven to be category one or zero vessels

    (scale is six to zero, with six being the lowest level of capability). When considering this in

    combination with the level of knowledge the vessel crew will have about the array design, marine

    coordination, and the previous low frequency of allision for internal navigation involving project

    vessels, the impact are assessed to be ALARP.

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    Third Party Vessels

    Regular operators were consulted as part of the NRA process and were asked to indicate whether

    they would enter the Hornsea Three array area or would navigate around it. Of those that

    responded, including during the Hazard Workshop, the majority indicated that they would not

    (intentionally) enter the Hornsea Three array area in part due to the small deviations that would be

    required in order to avoid it (as part of the entire journey and considering speed reduction they

    would likely make to enter the Hornsea Three array area (as with a port entrance channel)). When

    considering this alongside lessons learnt from other wind farms where negligible levels of

    commercial vessels have been recorded passing through arrays it is considered extremely unlikely

    that a commercial vessel would enter the Hornsea Three array area. It is noted that in other

    countries (such as the Netherlands) commercial vessels are excluded from entering offshore wind

    farms by the regulatory authority.

    The SAR guidance annexed to MGN 543 (implemented December 2016) notes SOLAS (IMO,

    1974) obligations for third party vessels and the potential need for vessels to enter wind farm array

    areas to render assistance. It notes “International practice for SAR response to persons in distress

    at sea includes alerting and notifying the nearest vessel(s) (this includes small vessels e.g. fishing

    vessels and leisure craft) to an incident location, and asking them to render assistance in

    accordance with the SOLAS regulations” (MCA, 2016).

    The following list identifies the maximum number of accommodation platforms and vessels on site

    during operation:

    • Up to three accommodation platforms or up to four OSVs which are likely to carry daughter

    craft;

    • Up to 20 CTVs;

    • Supply vessels which are likely to carry daughter craft; and

    • Marine traffic coordination 24/7.

    Although not specified within the Design Envelope, based on experience of other offshore wind

    farms it is assumed that there will be vessel support on site throughout the majority of the

    operation and maintenance phase that will help to ensure that all emergency response impacts

    can be effectively managed. Hornsea Three also plan to use helicopters on a regular basis and will

    have advanced medical provision on site.

    When considering Hornsea Three resources on site against the low number of third party vessels

    in the area it is highly probable that Hornsea Three project vessels would be the first to render

    assistance in the event of an emergency. It is therefore considered extremely unlikely that a

    third-party vessel would need to enter the Hornsea Three array area under any SOLAS

    (IMO, 1974) obligation. The risks associated with the requirement for third party vessels being

    required to render assistance are therefore considered negligible and ALARP.

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    Given the 1,000 m spacing between structures within the Hornsea Three array area, it is assessed

    (based on known manoeuvring and expert opinion) that navigational safety within the Hornsea

    Three array area will be improved compared to other consented, under-construction, or operational

    wind farms. Table 22.1 [omitted – see Table 6.2 above] presents the minimum spacing from

    consented wind farms or wind farms that are within the consent process with MCA and TH

    approval. It is noted that the minimum internal spacing committed to is significantly larger than

    other Round Three developments giving vessels more sea room to navigate and manoeuvre within

    the Hornsea Three array area (when considering turning circles and rate of turn).

    Experience at an Existing Offshore Wind Farm

    London Array offshore wind farm is an example of a wind farm that was consented, constructed

    and is currently operational with recreational and fishing activity. It was consented within a busy

    and seasonal area for small craft and a specific buoyed navigation channel (Fouglars Gat) was

    designed (in the position of an existing preferred route).

    Fishing and recreational vessels were identified from AIS data collected between 1 March 2016

    and 28 February 2017 (365 days) within the London Array offshore wind farm site boundary.

    During this period 140 unique recreational transits were recorded, with only eight vessels not using

    Fouglars Gat for the majority of their transit. Of those eight tracks and those that did not fully stay

    within Fouglars Gat it was seen that they also do not opt to remain fully within the available straight

    lines of orientation.

    During the 12 month period only 32 unique fishing vessel transits were recorded within the site

    boundary. Of the 49 tracks recorded, 23 broadcast a navigational status of “engaged in fishing”,

    with these near the southern boundary; the remaining 26 consisted of passages through the array,

    with vessels not, in the majority, following the main lines of orientation.

    Similar buoyed channels or additional international Aids to Navigation for use by recreational users

    and other small craft could be considered at Hornsea Three in consultation with the MCA, TH and

    key recreational users dependant on the final layout selected.

    Turbines have the potential to affect vessels under sail when passing through the Hornsea Three

    array area from effects such as wind shear, masking and turbulence. From previous studies of

    offshore wind farms it was concluded that turbines do reduce wind velocity by an order of 10%

    downwind of a turbine (RYA, 2015). The limited spatial extent of the effect is not considered to be

    significant, and similar to that experienced when passing a large vessel or close to other large

    structures (e.g. bridges) or the coastline. In addition, practical experience to date from RYA

    members taking vessels into other offshore wind farm sites indicates that this is not likely to be a

    significant issue.

    Given mitigation measures adopted as part of Hornsea Three and the potential for additional Aids

    to Navigation, the impact on internal navigation is considered tolerable with mitigation

    (Development Principles) and ALARP (moderate adverse significance in the Environmental

    Statement).

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    Increased Internal Allision for Commercial Fishing Vessels and Recreational Craft

    Presence of infrastructure within the Hornsea Three array area may increase vessel to structure

    allision risk for commercial fishing vessels navigating internally within the turbine array. The

    estimated allision frequencies of one every 5.74 years could be considered high when compared to

    other allision assessments carried out on developments within UK waters. However the model and

    the results reflect the significant maximum surface area assumed for all the structures that could

    be developed within the Hornsea Three array area against the medium density of fishing activity.

    The fishing allision model assumes that the fishing vessel density following development will

    remain the same as current levels; however in reality it is likely both that fishing activity will

    decrease and/or fishing vessels will adapt to the layout and continue to fish between the turbines

    (as seen at existing operational developments). The model does not assume what type of allision

    incident will occur and in reality the most likely would be a minor or low energy impact resulting in

    little or no damage to the vessels.

    During consultation, the Dutch Fishing Association VISNED also noted that in good weather fishing

    vessels are likely to transit through the wind farm. All foundation types including the jacket

    foundations considered in the maximum design scenario are assumed to be ALARP based on the

    minimum 1,000 m spacing and designed in measures in place to ensure that fishing vessels are

    able to safely passage plan transits and activity within the Hornsea Three array area. Further

    information is contained within volume 2, chapter 6: Commercial Fisheries.

    As with fishing vessels it is considered likely that recreational craft will adapt to navigating within

    Layout A given the minimum spacing of 1,000 m; recreational traffic levels are also very low within

    the Hornsea Three array area and negligible levels of recreational transits are likely to be seen.

    As noted MCA guidance states “that in order to minimise risks to surface vessels and/or SAR

    helicopters transiting through an OREI [sic], structures (turbines, substations etc.) should be

    aligned and in straight rows or columns” and “the developers (the Applicant) should plan for at

    least two lines of orientation unless they can clearly demonstrate that fewer is acceptable” (MCA,

    2016).

    Following consultation feedback as part of Section 42, the final layout will meet the Development

    Principles, including maintaining a single line of orientation, as referenced in section 9.5 [of the

    NRA].

    Looking at the issue of surface craft navigating within the array, the following factors gathered from

    consultation, the Hazard Workshop and marine traffic survey results make the case that Layout A

    will be tolerable with mitigation (Development Principles) (moderate adverse significance in

    the Environmental Statement):

    • Predicted levels of transiting vessels (recreational and commercial fishing) will be low

    compared to other constructed and/or consented wind farms;

    • While levels of fishing activity are high within some areas of the Hornsea Three array area,

    this will vary seasonally and annually. Some commercial fisheries representatives have

    indicated that their main concerns are over the foundation type used (minimal snagging risks)

  • Safety Justification for Single Line of Orientation Layout March 2019

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    and minimum spacing rather than the alignment. Overall, the majority of risk associated with

    internal navigation is related to vessels engaged in fishing rather than transiting;

    • Demersal trawlers active within the array area are expected to target specific fishing grounds,

    meaning that it is unlikely that the skippers would choose to fish along fixed lines of

    orientation, noting that fishing in the array area has been determined to be low (see

    section 5);

    • Consultation indicates that commercial vessels (in transit), other than commercial fishing

    vessels, will not navigate through the Hornsea Three array area;

    • The RYA stated that, given the very low level of recreational traffic within the Hornsea Three

    array area, they had no express concerns with the PEIR layouts and did not raise any further

    concerns during section 42 consultation;

    • With regards to the PEIR layouts the CA confirmed their general policy that wind farms should

    have “straight see-through channels between the turbines” while recognising that the Hornsea

    Three array is in an area of very light yachting and recreational traffic. The CA confirmed that

    the penalty of not having straight see-through “channels” at Hornsea Three “may prove

    minimal and therefore acceptable to many” therefore is assumed that the single line of

    orientation is a further improvement on random layouts.

    • The CA also noted that the penalty of extra time and distance incurred as a result of avoiding

    the Hornsea Three array area would mostly be minimal and thus it is likely that yachts and

    recreational craft may at the time of passage choose to avoid or be in a position where they

    should avoid the Hornsea Three array area;

    • The CA stated a preference for additional Aids to Navigation to be provided within the array;

    • Marine traffic survey data shows very low recreational vessel movements (especially when

    excluding the 500 Mile North Sea Race) and those that were in the area would be well

    equipped and experienced (given the distance offshore);

    • Aids to Navigation similar to those deployed at the London Array OWF could be used at the

    Hornsea Three array area to assist third party internal navigation this however would be

    decided by TH post consent;

    • Visibility is generally good or very good at the Hornsea Three array area. Appendix C

    includes further detail on visibility. The total percentage of time that the visibility is below 2 km

    is around 1.3%;

    • Cumulatively no other development will border the Hornsea Three array area;

    • It is unlikely that third party vessels will be required to perform SOLAS obligations within the

    Hornsea Three array area, given that Hornsea Three vessels are likely to be present on site;

    and

    • The Hornsea Three array area is largely out with the operational area for the RNLI and the

    MCA do not operate any surface craft assets within the southern North Sea.

    Given that this NRA is only able to consider indicative layouts, the following table identifies

    elements that should be considered when assessing site layout post consent, again excluding

    consideration for helicopter-based SAR operations. Table 8.1 identifies potential issues identified,

    risk ranking for indicative maximum design scenario Layout A and proposed mitigation for layouts

    to bring the effects into ALARP parameters. The information presented in Table 8.1 can be used to

    inform post-consent layout designs.

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    Table 8.1: Effects associated with navigation internally within the Hornsea Three array area

    Issue

    Receptor and

    Frequency of

    Receptor

    Sources Considered Risk and Proposed

    Mitigation

    Impact of 1,000 m minimum spacing for all structures on internal navigation

    Recreational craft – low frequency user

    No negative responses were received by recreational consultees.

    One thousand metre spacing would allow recreational craft to manoeuvre between structures given the maximum size of 24 m for recreational vessels (as per the Recreational Craft Regulations 2017 No. 737).

    Identification methods for structures currently required by standard guidance were considered sufficient.

    No further mitigation associated with minimum spacing required, draft DCO shall state minimum of 1,000 m between all structures.

    Impact of 1,000 m minimum spacing for all structures on internal navigation

    Commercial fishing vessels – medium frequency over the Hornsea Three array area

    Commercial fishing consultees favoured fewer and larger turbines and noted that the separation between turbines is more important than the regularity of the layout.

    No further mitigation associated with minimum spacing required, draft DCO shall state minimum of 1,000 m between all structures.

    Impact of no maximum spacing for structures on internal navigation

    Recreational craft – low frequency user

    At greater than 1,000 m spacing recreational craft may not be able to identify low level ID lighting of the next turbine that they are approaching. Therefore additional aids should be considered.

    Given the increased spacing and navigational information that will be provided for Hornsea Three, recreational vessels will have greater navigational knowledge, as well as space to sail and manoeuvre.

    Based on the shipping template within MGN 543, the turbines will be more visible with fewer echoes on marine Radar systems.

    Consultation raised no concerns about maximum spacing.

    No further mitigation associated with maximum spacing required, draft DCO shall state no maximum spacing.

    Impact of no maximum spacing for structures on internal navigation

    Commercial fishing vessels – medium frequency over the Hornsea Three array area

    Given the large spacing and increased navigational information that will be provided for Hornsea Three commercial vessels, they will have access to greater knowledge about the site and space to fish and manoeuvre.

    Consultation noted that fishing vessels prefer the largest spacing possible.

    No further mitigation associated with maximum spacing, required, draft DCO shall state no maximum spacing.

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    Issue

    Receptor and

    Frequency of

    Receptor

    Sources Considered Risk and Proposed

    Mitigation

    Impact of exposure to turbines

    Recreational craft – low frequency user

    Exposure is defined when a vessel is on a transit with turbines on either side of it within a “row” that will then potentially create effects as identified within the shipping template (Radar impacts within 1 nm).

    Time spent within the Hornsea Three array area and in proximity to structures will increase risk to vessels. At greater than1,000 m spacing exposure and thus effects will be significantly reduced compared to transits through existing wind farms with smaller spacing.

    The greater the spacing and non-alignment of turbines the lower the exposure time.

    Impact of exposure to turbines

    Commercial fishing vessels – medium frequency user over the Hornsea Three array area

    Impact of structure (including turbine) alignment

    Recreational craft – Low frequency user

    Non-alignment within a row is considered to be a non-grid layout where turbines are converging or diverging.

    RYA noted no concerns regarding the misaligned turbines that comprise the PEIR Layouts given the low frequency.

    CA noted that they preferred alignment but agreed with the low frequency. The CA section 42 consultation response also notes that increased spacing mitigates some of their concerns over alignment.

    Non-alignment can create confusion / disorientation within the Hornsea Three array area. Hornsea Three will provide navigational information via its Marine Coordination Centre to assist.

    Stakeholders did not raise any concern between alignment and allision risk.

    Given the increased size of other structures (such as substations and accommodation platforms), there are not anticipated to be any impacts from these structures being out of alignment, given that they will provide good Aids to Navigation for surface craft and be visible from a greater distance.

    No further mitigation required.

    Increased spacing inversely decreases the impact of misalignment.

    Recreational vessels are very low frequency within Hornsea Three and therefore the risk of a vessel becoming disorientated (when considering measures adopted as part of Hornsea Three) is negligible.

    There is no evidence to suggest that misalignment will directly affect allision risk but that misalignment could cause inconvenience by vessel operators becoming disorientated. Therefore if additional mitigations are in place to aid navigation the change in safety risk is assumed negligible.

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    Issue

    Receptor and

    Frequency of

    Receptor

    Sources Considered Risk and Proposed

    Mitigation

    Impact of structure (including turbine) alignment

    Commercial fishing vessels – medium frequency over the Hornsea Three array area

    Fishing consultation noted that fishing, including trawling and fly-shooting, would be possible in amongst the indicative layouts shown in the PEIR if the weather was suitable and the fish are present.

    For fishing, the separation between turbines is more important than the regularity of the layout.

    Given the increased size of other structures, there are not anticipated to be any impacts from these structures being out of alignment, given than they will provide good Aids to Navigation for surface craft.

    As with recreational craft, increased spacing inversely decreases the impact of misalignment.

    Given that Hornsea Project One and Hornsea Project Two do not directly border the Hornsea

    Three array area, there are not anticipated to be any impacts with cumulative internal alignment.

    9. Other Constraints

    Array or wake losses can account for as much as 10% of loss in energy yield within a wind farm,

    depending on the proposed layout and wind conditions. The material benefits of optimising layout

    are increased efficiency of turbine use and wind capture, maximising the availability of the turbine

    array to winds and thus increasing renewable energy production.

    While wake losses constitute one of the primary sources of production loss in offshore wind farms,

    it is possible to partially mitigate these losses through optimised layout and wind farm design. The

    primary mitigation is to increase the distances between turbines in the prevailing wind direction,

    thus allowing wake recovery. This mitigation method is not possible to implement to a great degree

    in a fixed grid layout. However, a SLoO layout would allow for this mitigation to be implemented.

    While the distance between the development lanes would be fixed, as described in the Layout

    Development Principles, it is possible to offset the turbines in alternating roles, thus increasing the

    distance between two turbines in the prevailing wind direction. This offers the project a way to

    optimize electricity production within the parameters set out by the Layout Development Principles.

    Detailed geophysical and geotechnical investigations are typically undertaken post financial

    decision due to the large costs involved. Ground investigations undertaken for previous projects

    have shown that glacial features historically present in this area of the southern North Sea have

    led to higher than expected spread and density of boulders (clearing boulders complicates site

    preparation and costs). Having the ability to site turbines away from such glacial geological

    features mitigates the need to clear wider areas of boulders and thus reduces the extent of

    interaction with the seabed.

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    10. Summary and Conclusion

    This report has considered the content of Volume 5, Annex 7.1: Navigational Risk Assessment of

    the Environmental Statement and materials produced in the examination process since the NRA

    was submitted in order to provide a justification for the safe implementation of a SLoO for the

    Hornsea Three array.

    In particular, key points of the safety justification which were discussed in consultation meetings

    with the MCA and TH in December 2017 have been considered in detail:

    • Vessel traffic levels within the array area are low;

    • Minimum spacing and foundation types are a greater concern to fishermen than the lines of

    orientation since activity will be dictated by targeted fishing grounds;

    • Hornsea Three resources on site are capable of providing an incident response; and

    • No other project borders the Hornsea Three array area.

    A number of other points supporting the case for a SLoO have been discussed and include the

    following:

    • Agreement between regular commercial operators in the area that commercial vessels would

    not generally use the array area for transiting;

    • Large minimum spacing between array structures eases CA concern over irregular layout

    patterns5;

    • RYA are unconcerned by the number of lines of orientation applied within the array layout

    (given the distance from shore and the low level of traffic);

    • Vessel traffic density is lower at Hornsea Three compared to the other Hornsea

    developments which were both consented with a SLoO;

    • Historical AIS data for a large existing array suggests that small craft do not consider the lines

    of orientation within the array layout, taking alternative routes instead;

    • The Applicant has provided evidence and shared expert helicopter pilot experience during

    examination and is of the view that SAR helicopters will be able to turn without risk of a

    collision with a turbine in the array area, including in poor visibility;

    • The minimum spacing for Hornsea Three is significantly greater than many existing UK

    offshore wind farms and gives vessels greater sea room to navigate and manoeuvre within

    the array area;

    • Historical incident data suggests a collision or allision incident involving Hornsea Three would

    not result in major damage to the vessel(s) or serious injury to persons, and any historical

    incidents would not be prevented by the inclusion of more than a SLoO;

    • Given the distance offshore and the presence of project vessels for Hornsea Three the

    likelihood of a SAR helicopter search operation being required are very low;

    5 Noting this comment was based on an irregular layout assessed at PEIR and not the SLoO assessed within the application.

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    • A suite of mitigation measures will be in place which minimise the risk to a vessel navigating

    within the array; and

    The number of Hornsea Three vessels anticipated to be on site during operation will be determined

    post consent but will be available to respond to safety incidents. Considering this, the likelihood of

    a third party vessel being required to enter the array area under SOLAS obligations is low. Based

    upon the Layout Development Principles, which the Applicant proposes should be secured by

    condition in the DMLs included in the DCO, Hornsea Three commits to:

    • Adhering to the guidance contained within MGN 543 (MCA, 2016) with the Layout

    Development Principles considered a refinement of the guidance specifically to meet the

    requirements of Hornsea Three;

    • Locating all s